We address the question: Can depressed mood in school-age (8 through 16 years) children be regarded as a syndrome analogous to adult depression? Adult DSM-III criteria for major depressive disorder have been shown to identify some adolescents and even preadolescents. The surface similarity calls for objective validation. We classify children as depressed by adult DSM-III criteria and contrast them with (a) a dysphoric but non-depressed sample and (b) an affectively normal control group. We draw upon reported correlates of major depressive disorder in adults for our analysis of these patient samples: (1) Neuropsychological test results indicative of right hemisphere malfunction, (2) laterality findings, both behavioral and electrophysiological, indicating right hemisphere overactivation, (3) difficulty in sustaining attention, (4) substantial familiality of depression, (5) positive dexamethasone suppression test, and (6) low urinary neurotransmitter metabolite levels. Adapting our methodology to children, we systematically examine our subject groups with respect to the above variables, to determine whether such findings characterize a subgroup of depressed or dysphoric children. We further determine whether such a syndrome of childhood major depressive disorder is limited by the child's age, and whether it can co-exist with the attention deficit disorder. Thus, we apply concurrently a set of measures (more usually deployed in isolation) to determine whether conjoint outcomes lend convergent validation to major childhood depressive disorder.